U.S. patent application number 10/945578 was filed with the patent office on 2006-03-23 for rapid exchange catheters having a sealed guidewire lumen and methods of making the same.
This patent application is currently assigned to SciMed Life Systems, Inc.. Invention is credited to Mark Mallaby.
Application Number | 20060064074 10/945578 |
Document ID | / |
Family ID | 36075039 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060064074 |
Kind Code |
A1 |
Mallaby; Mark |
March 23, 2006 |
Rapid exchange catheters having a sealed guidewire lumen and
methods of making the same
Abstract
Methods and devices for preventing fluid flow through the
relatively short guidewire lumen of a rapid exchange catheter. The
guidewire lumen for a rapid exchange catheter is provided with a
narrowed or sealed section allowing for passage of a guidewire
therethrough while preventing fluid flow while a guidewire is
disposed therethrough. The narrowed or sealed section extends for a
relatively short length of the guidewire lumen to avoid creating
excessive friction between the guidewire and the guidewire lumen.
In several embodiments the narrowed or sealed section is placed
proximal of the distal end of the guidewire lumen.
Inventors: |
Mallaby; Mark; (San Diego,
CA) |
Correspondence
Address: |
CROMPTON, SEAGER & TUFTE, LLC
1221 NICOLLET AVENUE
SUITE 800
MINNEAPOLIS
MN
55403-2420
US
|
Assignee: |
SciMed Life Systems, Inc.
|
Family ID: |
36075039 |
Appl. No.: |
10/945578 |
Filed: |
September 21, 2004 |
Current U.S.
Class: |
604/523 ;
264/109; 604/103.04; 604/264 |
Current CPC
Class: |
A61M 25/0169 20130101;
A61M 25/10 20130101; A61M 25/1034 20130101; A61M 25/1027 20130101;
A61M 2025/0183 20130101 |
Class at
Publication: |
604/523 ;
604/264; 604/103.04; 264/109 |
International
Class: |
A61M 25/00 20060101
A61M025/00 |
Claims
1. A rapid exchange catheter having a proximal end and a distal
end, the catheter comprising: an outer member having a proximal end
and a distal end; and an inner member having a proximal end and a
distal end; wherein: a guidewire port opens into the proximal end
of the inner member at a location along the outer member distal of
the proximal end of the outer member; the inner member extends
distally inside the outer member from the guidewire port beyond the
distal end of the outer member; the inner member is sized and
adapted to receive a guidewire therethrough, the inner member
having a first diameter along a majority of its length sufficient
to allow fluid passage therethrough while the guidewire is disposed
therethrough; and a seal is disposed within the inner member at a
location spaced from the distal end of the inner member.
2. The rapid exchange catheter of claim 1, wherein the seal is
located nearer the proximal end of the inner member than the distal
end of the inner member.
3. The rapid exchange catheter of claim 1, wherein the inner member
defines a first lumen and the outer member defines a second lumen,
the second lumen including a portion disposed between the inner
member and the outer member, wherein the inner member prevents
fluid flow from the second lumen into the first lumen.
4. The rapid exchange catheter of claim 1, wherein the seal is
formed at least in part of material of the inner member.
5. The rapid exchange catheter of claim 1 wherein the seal is
formed at least in part of material deposited within the inner
member.
6. A rapid exchange catheter having a proximal end and a distal
end, the catheter comprising: an outer member having a proximal end
and a distal end; and an inner member having a proximal end and a
distal end; wherein: a guidewire port opens into the proximal end
of the inner member at a location along the outer member distal of
the proximal end of the outer member; the inner member extends
distally from the guidewire port past the distal end of the outer
member; the inner member is sized and adapted to receive a
guidewire therethrough without allowing passage of a fluid
therethrough while the guidewire is disposed therethrough, the
inner member having a first diameter along a majority of its length
sufficient to allow fluid passage therethrough while the guidewire
is disposed therethrough; and the inner member includes a tubular
member having a necked portion spaced from the distal end of the
inner member.
7. The rapid exchange catheter of claim 6, wherein the inner member
includes a proximal tubular member and a bumper tip, the bumper tip
and proximal tubular member joining at a butt-joint, and the necked
portion is formed at the butt-joint using material from at least
one of the bumper tip and the proximal tubular member.
8. The rapid exchange catheter of claim 7, further comprising a
balloon having a proximal balloon waist, a distal balloon waist,
and a central balloon portion, wherein the distal balloon waist
overlaps the butt-joint between the bumper tip and the proximal
tubular member.
9. The rapid exchange catheter of claim 6, wherein the inner member
includes a proximal tubular member and a bumper tip, the bumper tip
forming a lap joint over the proximal tubular member, wherein the
necked portion is formed at the distal end of the proximal tubular
member beneath the bumper tip.
10. The rapid exchange catheter of claim 9, further comprising a
balloon having a proximal balloon waist, a distal balloon waist,
and a central balloon portion, wherein the distal balloon waist and
the bumper tip form a butt-joint over the proximal tubular
member.
11. The rapid exchange catheter of claim 6, wherein the necked
portion is located nearer the proximal end of the inner member than
the distal end of the inner member.
12. The rapid exchange catheter of claim 11, further comprising a
balloon having a proximal waist and a distal waist, the proximal
waist being secured to the outer member and the distal waist being
secured to the inner member; wherein the outer member defines an
inflation lumen and the inner member defines a guidewire lumen, the
inflation lumen being in fluid communication with the interior of
the balloon, the inflation lumen being fluidly isolated from the
guidewire lumen by the inner member.
13. The rapid exchange catheter of claim 6, wherein the inner
member defines a first lumen and the outer member defines a second
lumen, the second lumen including a portion disposed between the
inner member and the outer member, wherein the inner member
prevents fluid flow from the second lumen into the first lumen.
14. A method of fabricating a rapid exchange catheter having a
proximal portion and a distal portion with a proximal guidewire
port therebetween, the distal portion including a guidewire member
defining the majority of a guidewire lumen having a proximal end at
the proximal guidewire port and a distal end at the distal end of
the catheter, the method comprising providing a fluid flow stop
means for preventing fluid flow through the guidewire lumen at a
location proximal of the distal end of the guidewire lumen.
15. The method of claim 14, wherein the step of providing a fluid
flow stop means includes inserting a seal member therein.
16. The method of claim 14, wherein the step of providing a fluid
flow stop means includes creating a necked portion of the guidewire
lumen by applying heat to the guidewire member.
17. The method of claim 16, wherein the rapid exchange catheter
includes an outer member and the guidewire member, the guidewire
member extending distally from the proximal guidewire port inside
the outer member, the rapid exchange catheter also including a
balloon having a proximal waist secured to the outer member and a
distal waist secured to the guidewire member, wherein the step of
creating a necked portion of the guidewire lumen is performed as
part of a process for securing the distal balloon waist to the
guidewire member.
18. The method of claim 17, wherein the guidewire member of the
rapid exchange catheter includes a proximal tubular member and a
bumper tip, and wherein the step of creating a necked portion
comprises: placing an end of the bumper tip adjacent a distal end
of the distal balloon waist over the proximal tubular member;
placing a mandrel inside the proximal tubular member and/or bumper
tip, the mandrel having a stepped portion having a lesser diameter
than other portions of the mandrel, such that the stepped portion
is adjacent a distal end of the proximal tubular member; and
applying heat to secure the bumper tip, balloon, and proximal
tubular member together; wherein the necked portion is formed at a
location corresponding to the distal end of the proximal tubular
member.
19. The method of claim 17, wherein the inner member of the rapid
exchange catheter includes a proximal tubular member and a bumper
tip, and wherein the step of creating a necked portion comprises:
placing a proximal end of the bumper tip adjacent a distal end of
the proximal tubular member to form a butt-joint beneath the distal
balloon waist; placing a mandrel inside the proximal tubular member
and/or bumper tip, the mandrel having a stepped portion having a
lesser diameter than other portions of the mandrel, such that the
stepped portion is adjacent the butt-joint; and applying heat to
secure the bumper tip, balloon, and proximal tubular member
together; wherein the necked portion is formed at a location
corresponding to the butt-joint.
20. The method of claim 14, wherein the step of providing a fluid
flow stop means includes providing a mandrel having a first
diameter at a first location and a second diameter at a second
location, the second diameter being less than the first diameter,
and the necked portion is formed by: inserting the mandrel into the
guidewire lumen; and applying heat to the guidewire member at a
location corresponding to the second location on the mandrel to
reduce the inner diameter of the guidewire member.
21. The method of claim 14, wherein the guidewire lumen extends
distally from the proximal guidewire port, the proximal guidewire
port being constructed in a molding step, wherein the fluid flow
stop means is formed during the molding step.
22. The method of claim 14, wherein the fluid flow stop means is
provided closer the proximal end of the guidewire lumen than the
distal end of the guidewire lumen.
23. The method of claim 22, wherein the relatively short portion is
constructed relatively near the guidewire port.
24. A method of using a rapid exchange catheter comprising:
providing a rapid exchange catheter having a proximal end, a distal
end, a proximal section, a proximal guidewire port, and a distal
section, the distal section defining a greater number of lumens
than the proximal section, the distal section including a guidewire
member having a proximal end opening into the guidewire port and a
distal end extending to the distal end of the catheter, the
guidewire member having a fluid stopping structure therein adapted
to prevent fluid flow through the guidewire member when a guidewire
is disposed through the fluid stopping structure, the fluid
stopping structure being disposed proximal of the distal end of the
guidewire member; inserting a proximal end of a guidewire to the
distal end of the guidewire member; manipulating the guidewire
and/or rapid exchange catheter to cause relative movement between
the two to advance the guidewire proximally through the guidewire
member up to the fluid stopping structure; and manipulating the
guidewire and/or rapid exchange catheter to cause relative movement
between the two to cause the guidewire to pass proximally of the
fluid stopping structure.
25. The method of claim 24, wherein the fluid stopping structure is
provided nearer the proximal end of the guidewire member than the
distal end of the guidewire member.
Description
FIELD OF THE INVENTION
[0001] The present invention is related to the field of medical
devices. More particularly, the present invention is related to
rapid exchange catheter technologies.
BACKGROUND OF THE INVENTION
[0002] Catheters are used in a variety of minimally invasive
medical procedures. A major portion of the catheter field involves
catheters that track over a guidewire, such as angioplasty
catheters that are used to advance an inflatable member over a
guidewire to a desired vascular location. One advancement in this
field has been the use of rapid exchange catheters in place of
standard over-the-wire catheters.
[0003] A standard over-the-wire catheter typically tracks over a
guidewire over its entire length such that, in order to maintain a
distal guidewire location while exchanging the catheter, a
guidewire extension or very long guidewire is used. To exchange the
standard over-the-wire catheter, the guidewire is held in place
while the catheter is withdrawn. The proximal end of the guidewire
is held until the distal end of the catheter exits the patient's
body, while the distal end of the guidewire remains in the desired
location, meaning that the guidewire, during exchange, must be
twice as long as the catheter.
[0004] A rapid exchange catheter tracks over the guidewire for only
a short distal portion of the catheter. Examples of rapid exchange
catheters, their use, and methods for making such catheters are
illustrated by Williams et al. in U.S. Pat. No. 6,409,863, the
disclosure of which is incorporated herein by reference. The
catheter shown by Williams et al. includes an outer member and a
distally located inner member, with a balloon proximal end attached
to the distal end of the outer member and a balloon distal end
attached to the distal inner member. A proximal guidewire port is
located distal of the proximal end of the catheter, with the distal
inner member opening at its proximal end to the proximal guidewire
port, and extending to the distal end of the catheter.
[0005] One difficulty which can arise with some rapid exchange
catheters is that an inner member defining the distal guidewire
lumen may allow passage of fluid therethrough. Because the proximal
guidewire port is typically in view of fluoroscopic instruments,
passage of contrast fluid used to visualize the treatment location
(for example, the location of a lesion in a blood vessel)
proximally through the guidewire lumen can be misinterpreted as
indicating device failure during inflation of a distally located
balloon. Reducing the diameter of the guidewire lumen to prevent
fluid passage, however, can make it more difficult to push the
catheter over the guidewire. Reducing the slidability of the
catheter with respect to the guidewire (and vice-versa) can make it
more difficult to maintain and manipulate guidewire position,
thereby making the physician's task of advancing a catheter over
the guidewire more difficult.
SUMMARY OF THE INVENTION
[0006] The present invention, in an illustrative embodiment,
includes a rapid exchange catheter having an outer member and an
inner member defining a guidewire lumen, with the outer member
including a proximal guidewire port located distally of the
proximal end of the catheter. The inner member extends from the
proximal guidewire port to the distal end of the catheter. The
inner member includes a fluid stop portion (less than its total
length) configured to prevent fluid flow therethrough when a
guidewire is disposed through the inner member. In several
embodiments, the fluid stop portion is disposed proximal the distal
end of the inner member. In one such embodiment, a seal is disposed
within the inner member. In another such embodiment, the inner
member includes a necked portion proximal its distal end.
[0007] The present invention, in additional illustrative
embodiments, includes methods of making a rapid exchange catheter
having an inner member adapted to receive a guidewire. The inner
member is further adapted to prevent fluid flow therethrough when a
guidewire is disposed through the inner member. In one such
embodiment, a seal is placed in the inner member. In another
embodiment, a portion of the inner member is subjected to pressure
and heat while disposed over a mandrel having a tapered or necked
portion, such that a portion of the inner member necks down to a
narrowed diameter for a length less than the total length of the
inner member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 shows a portion of a rapid exchange type catheter in
cross section;
[0009] FIG. 2 shows, in partial cross section, an illustrative
rapid exchange catheter proximal guidewire port and proximal
portion of a guidewire lumen having a fluid blocking means;
[0010] FIG. 3 shows, in partial cross section, an illustrative
distal portion of a guidewire lumen for a rapid exchange catheter
having a fluid blocking means;
[0011] FIG. 4 shows, in partial cross section, mandrels and tubular
members configured for a step in constructing a rapid exchange
catheter with fluid blocking means in a proximal portion of the
distal guidewire lumen;
[0012] FIG. 5 shows, in partial cross section, an illustrative
rapid exchange proximal guidewire port that may be constructed as
shown in FIG. 4;
[0013] FIG. 6 shows, in partial cross section, mandrels and tubular
members configured for a step in constructing an alternative rapid
exchange catheter with fluid blocking means in the distal portion
of the distal guidewire lumen;
[0014] FIG. 7 shows, in partial cross section, a distal end of an
illustrative rapid exchange catheter that may be constructed as
shown in FIG. 6;
[0015] FIG. 8 shows, in partial cross section, another distal end
for an illustrative rapid exchange catheter; and,
[0016] FIGS. 9A-9B illustrate, in schematic section views, a rapid
exchange proximal guidewire port before and after a port molding
method of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] The following detailed description should be read with
reference to the drawings. The drawings, which are not necessarily
to scale, depict illustrative embodiments and are not intended to
limit the scope of the invention.
[0018] As used herein, the term "rapid exchange" should be
understood as imparting the same or similar meanings as other terms
used in the catheter arts such as single operator exchange. In
particular, "rapid exchange catheter" includes any catheter
designed to enable exchange of a catheter placed using a guidewire
without requiring a guidewire extension or guidewire that is
substantially longer than the catheter itself. While much of the
following description and several of the figures illustrate balloon
catheters, other catheter types may incorporate the improvements
herein, including, for example, fluid infusion cannulas, cutting
instruments, non-balloon self-expanding stent delivery catheters,
and/or atherectomy devices. Vascular and non-vascular (such as
biliary or uretogenital) uses are contemplated.
[0019] FIG. 1 illustrates relevant features of a rapid exchange
catheter 10. The catheter 10 includes a proximal end 12 and a
distal end 14. An outer tubular member 16 defines an inflation
lumen, and an inner tubular member 18 defines a guidewire lumen
from a guidewire port 20 to the distal end 14 of the catheter 10.
The proximal end of a balloon 22 is secured to the distal end of
the outer tubular member 16. The distal end of the balloon 22 is
secured near the distal end of the inner tubular member 18. While
shown as a butt-joint, the balloon 22 is often bonded to the outer
tubular member 16 by a process performed on an overlap of the two.
The balloon 22 may be secured by any suitable manner, for example,
using heat or welding methods, or by the use of an adhesive. The
outer tubular member 16 includes a proximal portion extending from
the proximal end 12 to the guidewire port 20 and a distal portion
extending from the guidewire port 20 to the balloon 22.
[0020] A number of designs for and additional features of a rapid
exchange catheter 10 have been developed. For example, the outer
tubular member 16 may be made up of several tubes connected to one
another including hypotubes, polymeric tubes, and/or reinforced
polymeric tubes. The balloon 22 may be inelastic or elastic. Rather
than a side exit as shown in FIG. 1, the guidewire port 20 may face
a generally axial direction. Core wires, transition support
elements, and the like may also be provided. A number of radiopaque
markers may be provided at various locations, as desired. The
inclusion or addition of any of these features should be understood
as being optional features of the following illustrative
embodiments of the present invention. Furthermore, the exact
location and manner of securement/attachment between the various
elements can vary widely as further optional features of the
following illustrative embodiments. Finally, the materials used are
also a matter of design choice and may vary widely within the scope
of the present invention.
[0021] FIG. 2 illustrates in cross section a guidewire port 36. The
catheter 30 is illustrated having an outer member 32 and an inner
member 34. During use, a difficulty which can arise is the backflow
of contrast fluid from the distal end (not shown) of the catheter
30 through the inner member 34 (which defines a guidewire lumen) to
the guidewire port 36. The contrast fluid can then exit the
catheter shaft and can appear, under fluoroscopy, to indicate
catheter failure due to a leak at the guidewire port 36.
[0022] For example, a radiopaque fluid or saline including a
radiopaque material may be used to inflate a balloon disposed on
the distal end of the catheter 30. If radiopaque fluid was
previously used to visualize the area of treatment at the distal
end of the catheter, it may (unless prevented from doing so) flow
up the inner member 34 to the guidewire port 36, and exit the
catheter 30 there. If this occurs, it can appear as though the
inflation fluid were leaking at the guidewire port 36. Observation
of the fluid exiting at the guidewire port 36 can unnecessarily
cause a practitioner to believe that the inflation lumen is
leaking, halt the procedure, and remove and discard the catheter
30. This is costly in terms of practitioner and procedure time,
materials and products, and, most importantly, patient discomfort
and stress.
[0023] To prevent such leakage or flow through the inner member 34,
the illustrative catheter 30 is provided with a fluid stop
structure 38, illustrated as a narrowing or bump in the lumen
defined by the inner member 34. The fluid stop structure 38 may be
a deposited material or an inserted piece of material such as a
plastic, wax, leather, foam, rubber, artificial rubber, or any
flexible material that can prevent fluid flow through the inner
member while a guidewire is disposed therein. Preferably the fluid
stop structure 38 is designed, coated, or otherwise constructed to
avoid creating undue friction with a guidewire (not shown) passing
therethrough. By including the fluid stop structure 38, radiopaque
fluid is prevented or substantially prevented from exiting the
catheter at the guidewire port 36.
[0024] FIG. 3 illustrates an alternative sealing structure. In FIG.
3, a catheter 40 with balloon 42 and inner member 44 includes a
sealing structure shown as seal 46 disposed near the distal end of
the guidewire lumen. The seal 46 may be, for example, a seal
material or seal itself secured inside of the inner member 44.
Alternatively, the inner member 44 may be provided as including an
internal lumen irregularity that functions as a seal 46 to prevent
fluid flow through the inner member 44 when a guidewire (not shown)
is disposed therein. By moving the seal 46 away from the distal tip
of the catheter 40, it becomes easier to backload a catheter over a
guidewire (loading by inserting the proximal end of the guidewire
into the distal end of the catheter 40 and advancing the catheter
40 over the guidewire).
[0025] FIG. 4 illustrates a step in a process of making a rapid
exchange type catheter having a fluid blocking feature in its
distal inner member. In particular, the catheter 50 is shown having
integral parts including a proximal member 52, a distal outer
member 54, and a distal inner member 56. The proximal end 58 of the
distal inner member 56 is shown as fitting onto a reduced size
portion of a distal mandrel 64. A proximal mandrel 62 passes
through the proximal member 52 past a guidewire port 60.
[0026] Several designs may be used for the proximal end 58 of the
distal inner member 56. The proximal end 58 of the distal inner
member 56 may be formed as a tapered portion. Alternatively, the
distal inner member 56 may be a simple tubular member, with a
triangular portion cut from its proximal end 58 to allow the distal
inner member 56 to be compressed around the distal mandrel 64. In a
preferred embodiment, the distal inner member 56 is a tubular
member that is shaped over the distal mandrel 64 during a
heat-welding step in which the proximal member 52 is attached to
the distal outer member 54 and distal inner member 56 to form the
port joint or guidewire port 60. To achieve such a structure, the
proximal mandrel 62 may include a distal end having a crescent or
half-moon transverse cross-sectional shape such that it can
partially surround the distal inner member 56. In at least one
embodiment, the proximal end 58 of the distal inner member 56 is
sized to allow relatively easy passage of a guidewire therethrough,
while preventing undesired fluid flow.
[0027] One advantage of the embodiment of FIG. 4 is that it can be
even easier to introduce a guidewire to the distal end (not shown)
of the catheter than with the embodiment in FIG. 3. This is due to
the fact that the narrowed portion of the inner members (44, 56) is
the location at which the greatest friction will likely occur when
a guidewire is advanced or withdrawn. By placing the fluid
restricting feature away from the distal end of the catheter, it
becomes possible to advance the guidewire through a portion of the
inner member before reaching this friction-creating point. Further,
the opening at the distal end becomes bigger, and the inner/outer
members may provide column strength for easing passage of the
guidewire without buckling either the catheter or the
guidewire.
[0028] For example, in several rapid exchange embodiments, the
method of introduction over a guidewire includes back-loading the
distal end of the catheter over the proximal end of a guidewire.
This method can be difficult using, for example, a structure as
shown by Fitzmaurice et al. in U.S. Pat. No. 6,190,358, which shows
necking of the guidewire member at its distal tip. The distal tip
will typically be quite soft and flexible, sometimes taking the
form of a "bumper" tip to avoid damaging blood vessels during
advancement. Typically the proximal end of a guidewire has the
greatest diameter and stiffness for the guidewire. Getting the
proximal tip of the guidewire into such a delicate and soft
structure without damaging the catheter can be a challenge,
particularly given that the practitioner will usually be wearing
gloves. Furthermore, placing the necked portion right at the distal
tip may stiffen the "bumper" tip, reducing its effectiveness in
preventing damage to surrounding tissue.
[0029] FIG. 5 illustrates, in section, the catheter 50 from FIG. 4
after a welding/fusing or other attachment step. It can be seen
that the catheter includes a proximal member 52, distal outer
member 54, and distal inner member 56. A guidewire port 60 is
located at a port joint. Near the guidewire port 60 is a fluid
restriction feature 66 shown as a narrowing of the guidewire lumen
70 defined by the distal inner member 56. Note that it is not
necessary for the distal inner member 56 to remain in contact with
the distal outer member 54 distal of the guidewire port 60, where
the catheter may assume a generally coaxial/concentric
configuration. The inflation lumen 68 may have a crescent shape
across the port joint near the guidewire port 60, and may take an
annular shape distal of the guidewire port 60, as desired. The
integral parts 52, 54, 56 are shown separately for illustrative
purposes. However, near the guidewire port 60 these parts will
typically fuse and blend together to a certain extent.
[0030] FIG. 6 illustrates, in section, a method for providing a
fluid blocking feature near the distal end of a rapid exchange
catheter. The catheter 100 is illustrated having a balloon 102
attached at its distal end to an inner tubular member 104 and a
distal bumper tip 106. The use of a very soft or atraumatic bumper
tip 106 makes advancement of a catheter in a blood vessel easier by
improving trackability and avoiding vessel trauma. Such softened
tips may be used in other environments as well. The balloon 102 is
secured by a heating process (such as a laser welding process) over
the butt-joint between the inner tubular member 104 and the bumper
tip 106. For the illustrative embodiment of FIG. 6, before the
heating step to secure the balloon 102 to the inner tubular member
104 and the bumper tip 106, mandrels 108, 110 are passed into the
bumper tip 106 and inner tubular member 104, respectively. The
mandrels 108, 110 help maintain the shape and patency of the lumens
for the inner tubular member and bumper tip. To provide a fluid
blocking feature, the tips of one or both of the mandrels may be
notched, tapered or trimmed to provide a narrowed mandrel
section.
[0031] After the various elements shown in FIG. 6 are subjected to
a heat bonding step, the mandrels 108, 110 are removed and the
configuration shown in FIG. 7 is the result. In particular, the
balloon 102 is secured over the inner tubular member 104 and the
bumper tip 106. A fluid blocking feature 112 has been created by
plastic deformation during the heating step, with one or both of
the inner tubular member 104 and bumper tip 106 being deformed
around the mandrels 108, 110 to create a narrowed lumen section or
lip. The fluid blocking feature 112 is preferably sized to block
fluid flow through the combination of the inner tubular member 104
and bumper tip 106 when a guidewire is disposed therethrough.
Because the fluid blocking feature 112 is not at the distal tip of
the bumper tip 106, instead being disposed proximally thereof, it
may be easier to backload a guidewire (not shown) with the catheter
100.
[0032] Typically the sizing of such catheters renders the distance
from the distal end for the fluid blocking feature 112 relatively
long even though appearing, in terms of absolute magnitude, rather
short. As an example, the bumper tip 106 in some embodiments may
have a length in the range of about 2-4 mm. A fluid blocking
feature as shown in FIGS. 6-7 would, therefore, be in the range of
2-4 mm from the distal end of the catheter. As such, the distal
opening of the inner member may be large enough to facilitate
backloading of a guidewire therein, with the changing diameter of
the guidewire lumen guiding the guidewire past the fluid blocking
structure.
[0033] FIG. 8 shows, in partial cross section, another distal end
for an illustrative rapid exchange catheter. The catheter 120
includes a balloon 122, an inner member 124, and a bumper tip 126.
In the illustrative embodiment, the balloon 122 and bumper tip 126
form a butt-joint over the inner member 124. These three elements
may be secured to one another by placing mandrels therethrough and
subjecting the joint(s) to heat. By using mandrels having a stepped
or tapered portion, a fluid blocking structure 128 may be formed at
the distal end of the inner member 124. In the illustration, the
fluid blocking structure 128 is formed using material from the
distal end of the inner member 124. Such a formation may optionally
be further facilitated by the use of materials for the three
elements shown 122, 124, 126 such that the inner member 124 flows
more readily at a given temperature than the balloon 122 or bumper
tip 124.
[0034] A number of molded port joints and subassemblies are
illustrated in copending application Ser. No. 10/653,375, filed
Sep. 2, 2003 and entitled CATHETER INCLUDING A UNIBODY DISTAL
GUIDEWIRE PORT AND METHOD OF MANUFACTURE, the disclosure of which
is incorporated herein by reference. Modification of the mandrels
illustrated therein may be performed in accordance with the present
invention to provide fluid flow stops in the guidewire lumens of
embodiments therein.
[0035] For example, FIGS. 9A-9B illustrate, in schematic section
views, mandrels and tubular members disposed prior to performing a
molding step to construct an insert molded port joint, and the port
joint once so created. As illustrated in FIG. 9A, a port mold 200
is provided defining a molding volume 202. A proximal member 204 is
partly inserted to the port mold with a mandrel 206 extending
distally therefrom. The mandrel 206 extends through the molding
volume 202 into a space between the distal outer member 208 and
distal inner member 210. The mandrel 206 may include a proximal
round section and a distal section having a taper or that is
crescent shaped to fit in the space between the distal inner member
210 and distal outer member 208.
[0036] A first guidewire mandrel 212 is provided extending from the
port mold 200 into the distal inner member 210. As can be seen, the
end of the first guidewire mandrel 212 includes a portion of
reduced diameter. A second guidewire mandrel 214 extends through
the distal inner member 210 from its distal end near the proximal
end of the distal inner member 210. The second guidewire mandrel
214 may be shaped at its end to partially mate with the first
guidewire mandrel 212, as shown. However, there is a region where
the first guidewire mandrel 212 has a lesser diameter than that of
the distal inner member 210 without the second guidewire mandrel
214 extending thereto.
[0037] An injectate material is then forced into the port mold 200.
The injectate material will be typically hot, and will provide
pressure as well. The combination of heat and pressure then causes
the members 204, 208, 210 to be secured together. As shown in FIG.
9B, when the injection/heating/pressure step is completed, the
members 204, 208, 210 are secured to one another either directly or
via the injected material 216, which surrounds and adheres to each
member 204, 208, 210. A guidewire port 218 is provided by the use
of the mandrels 212, 214 (not shown). A guidewire passage includes
the interior of the guidewire port 218 as well as the interior of
the distal inner member 210. It can be seen that a fluid blocking
feature 220 resides therein, as a result of the effects of heat and
pressure on the area of the distal inner member 210 near where the
smaller diameter distal end of the first guidewire mandrel 212 was.
Meanwhile, an inflation lumen 222 has been maintained going through
the port joint itself from the inner member 204 to the lumen
between the distal inner member 210 and the distal outer member
208.
[0038] Those skilled in the art will recognize that the present
invention may be manifested in a variety of forms other than the
specific embodiments described and contemplated herein.
Accordingly, departures in form and detail may be made without
departing from the scope and spirit of the present invention as
described in the appended claims.
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